1. Field of the Invention
The present invention broadly relates to optical systems, and deals more particularly with the automated selection of optical systems using standardized optical components.
2. Prior Art
A variety of optical systems are commonly used to perform inspection or monitoring processes in industrial applications. In some cases, human operators use the optical systems to view objects, surface features or other phenomenon of interest. In other cases, optical systems are used as part of “machine vision” systems to automatically perform inspection or recognition processes. Machine vision systems typically include a camera or similar recording device which includes an optical lens for imaging an object onto a sensor comprising either a linear or two dimensional array of pixels that electronically record an image of the object and convert it to a digitized pixel stream that is processed by a machine vision processor. The processor typically forms part of a programmed computer that operates on the digitized pixel stream to determine whether certain characteristics are present in the image, and displays the recorded image or feature of interest on a monitor.
Optical systems of the type mentioned above are often designed using a number of relatively standard, off-the-shelf components, such as specialized lens systems, illumination sources, focusing mechanisms and camera mounts. A variety of lenses may be employed, depending upon the application, such as micro lenses, macro lenses, zoom lenses, and other lens combinations which are well known in the art.
In designing optical lens systems for machine vision and other applications, a variety of well known formulas and guidelines have been developed to aid in selecting an optical system for specific industrial applications. For example, it is known that as the numerical aperture increases, the depth of field decreases and resolution increases. As magnification increases, the field of view decreases and more light may therefore be needed. Further, for example, it is well known that magnification is developed in two ways—either by using different lenses and different magnifications at the camera, or by using camera and monitor combinations that develop magnification between themselves. Similar rules and guidelines have been developed relating to depth of field, depth of focus, distortion, resolution, object-to-image distance, working distance, etc.
In the past, in order to specify an optical system for a specific application, such as a machine vision inspection application, an optical system engineer would manually review the requirements for the application and then select a combination of standardized optical components that function in combination to meet the application requirements. While this prior “manual” approach to specifying optical systems generally provided satisfactory results, the process could be time consuming, and required an involvement of an individual with considerable optical background (which defeats the “one stop shopping” concept of using the internet). Moreover, there could be delay in providing a customer or user with the final results of the design process.
Accordingly, there is a need in the art for an automated method of selecting an optical system which overcomes each of the disadvantages of the prior art discussed above.